Re: Source of Avogadro's number

["Fred Maess" <fred_maess@fernald.gov>]

     The number of atoms in a mole is that number of Carbon-12 atoms in 12 
     grams of Carbon-12.  This is the definition set forth by the 1969 
     International Committee on Weights and Measures.  
     
        It could also be said in this form:
     
     Mole - The amount of a substance that contains as many elementary 
     units (atoms, molecules or ions) as there are atoms in 12grams of 
     Carbon-12.
     
        This only applies to the gram-mole however.  You can also express 
     these things in lb-moles, kg-moles, ton-moles or whatever mass unit 
     you desire.
     
     Frederick Maess
     fred_maess@fernald.gov
     (513) 648-5089


______________________________ Reply Separator _________________________________
Subject: Source of Avogadro's number
Author:  radsafe@romulus.ehs.uiuc.edu at FE-INTERNET
Date:    9/27/96 10:52 AM


Although this thread is getting quite old, I would like to know what the 
SOURCE of Avogadro's number is.  For instance, the second is defined as a 
certain number of oscillations (disintegrations?) of something - I forget 
what - and the  meter is defined as length of - - well, I've forgotten that, 
too.
     
So what defines the number of atoms in a mole?  Convention?  A physical 
measurement?
     
Scott O. Schwahn, CHP
Accelerator Division, M.S. 12A1
Thomas Jefferson National Accelerator Facility 
12000 Jefferson Avenue
Newport News, VA 23606
(757)269-7551 (w)
(757)269-7363 (fax)
schwahn@cebaf.gov